a. Field of the Invention
The present invention relates to an improved cap with an inside stopper for use in receptacles, and particularly relates to an improved cap with an inside stopper, wherein said inside stopper is designed to fit in the opening of the receptacle to enhance the tight sealing effect while the cap proper and the inside stopper are detachable from said opening simultaneously or separately at the time of using the receptacle.
B. Description of the Prior Art
There have hitherto been proposed various modes of caps with an inside stopper for use in receptacles and which are intended to be superior in the tight sealing effect. However, as a matter of fact, none of the caps of this kind available on the market at present has proved satisfactory to meet the demand of users to perfection. For instance, the commercially available cap shown in FIG. 8 wherein the inside stopper and the cap proper are detached separately is not easy to handle. In the case of a cap wherein the cap proper and the inside stopper are formed as an integral unit it is defective in that there frequently occurs an offset between the centers of the cap and the inside stopper, causing a gap to exist between the exterior of the side-wall of the inside stopper and the inside wall of the opening of the receptacle and leakage of the liquid contained in the receptacle proper through said gap.
In the meantime, various studies of caps giving priority to achievement of a tight sealing effect thereof have also been made. But, the caps proposed as the result of those studies have been defective in that they are very intricate in construction, requiring a high technical skill in manufacturing thereof.